Brain stimulation devices can be used for treatment of depression and/or a number of neurological disorders and chronic degenerative diseases.
U.S. Pat. No. 7,295,880 issued Nov. 30, 2007 to Gielen teaches methods and devices for monitoring the battery life of an implantable deep brain stimulation device including modifying the therapy to increase the battery life of the implantable pulse generator to allow the patient time to seek medical attention.
U.S. Patent Pub. No. US2005/0165458 by Boveja published on Jul. 28, 2005 teaches using electroconvulsive therapy to the brain and pulsed electrical stimulation to the vagus nerve using implantable pulse generator and electrodes on the exterior of the head. The therapy can be in any order, ay combination or any sequence. The implantable device can include wireless communication capability.
U.S. Patent Publication No. 210/0280572 by Meadows, et al., published on Nov. 4, 2010, is a continuation of U.S. Patent Pub. 2005/0055064, now abandoned, which is a continuation-in-part of U.S. Pat. No. 6,920,359 issued on Jul. 19, 2005, teaches an open loop deep brain stimulation system that uses a multichannel implantable pulse generator small enough to be implanted directly into the cranium of the patient. The system also has support for two leads, each lead having plural electrodes; and the system including a wireless link. The publication does not describe use of the system such as cathode and anode configuration, pulse duration strength such as current and voltage, or directionally of the pulse, etc.
Montgomery, et al “Deep Brain Stimulation Programming” publication, University of Wisconsin, (Feb. 20, 2006), is directed toward electroconvulsive therapy as electrical stimulation to the vargus nerve using an implantable or external pulse generator and ECT electrodes on the head. The implantable device can include wireless communication capability. Montgomery takes an in depth review of deep brain stimulation with a single lead having multiple ring contacts including the implantation of the lead, the stimulation characteristics, results, adverse effects and possible causes and remedies.
A number of neurological disorders and many neurodegenerative diseases like Parkinson's disease involve, or eventually progress to involvement of both brain hemispheres; requiring electrode implants in both sides. Bilateral implanted electrodes can be powered by two separate implantable pulse generators as (IPGs) shown in FIG. 1a or by one that serves both electrodes as shown in FIG. 1b. If there are two separate IPGs, their pulses are unsynchronized. If there is only one dual-channel IPG that serves both electrodes, the pulses are exactly synchronized, energizing contacts at the same time.
There is good evidence that bilateral stimulation has a synergetic effect on therapeutic efficacy, suggesting that target sites are close enough for the contralateral electrical fields to interact. Normally, the voltages being used clinically in the subthalamic nucleus (STN), for example, are in the range of 2 to 3 V and the electrode impedance is typically between 750 and 1500 ohms. The best estimates of current spread thus translate into distances of 2 to 3 mm radially from a monopolar contact (approximately 1-1.5 mm diameter per mA, decreasing in stimulating intensity with distance as shown in FIGS. 2a and 2b. 
FIG. 2a illustrates monopolar current filed produced with monopolar stimulation. FIG. 2b is a graph showing the relative monopolar loss of voltage in regard to relative distance from the cathode with two commonly used leads, results from the 3387 lead is shown with circles while the results with the 3389 lead are shown with squares. As shown in the graph, as the distance from the cathode increases, the relative voltage decreases with both the 3387 lead and the 3389 lead.
Typically, monopolar stimulation is first tested with a single contact on the lead set as the cathode and the pulse generator and lead set as the anode. Although generally one contact is used as the cathode, it is occasionally useful to activate two adjacent contacts for a broader field of current diffusion. Bipolar stimulation is accomplished using one electrode contact as the anode and an adjacent electrode as the cathode. This configuration is advantageous if adverse effects due to current spread to adjacent structures limits efficacy of stimulation. Bilateral anode and cathode contacts elongate and diffuse the current field as shown in FIG. 3, allowing stimulation of nearby brain sites while minimizing stimulation of more distant sites in between in other directions. As described in relation to the monopolar current field shown in FIG. 2a, the strongest stimulation occurs near the electrode contacts in the bipolar stimulation as well.
A problem associated with the previously described deep brain stimulation devices is that when the contact is displaced more substantially medial-lateral or anterior-posterior to the target center, or there is an electrode shift, the only option now is for another surgery to re-implant them.
What is need is a computerized alternative that resolves the problem without the risks incurred with additional brain surgery.